The use of error feedforward for error spectrum shaping in 2-D separable-denominator digital filters

摘要

Due to finite word length effects, the degradations of filter characteristics occur in the implementation of recursive digital filters. One of them is a filter output noise caused by roundoff errors in the product quantization. This kind of noise can be reduced by applying an error-spectrum-shaping technique. The error spectrum shaping is usually based on the feedback of the roundoff errors and rarely uses its feedforward. This paper develops an error-spectrum-shaping technique in two-dimensional separable-denominator digital filters. The proposed technique is based on not only the feedback but also the feedforward of the roundoff errors. Here1 powers-of-two coefficients are also used in the error feedback and feedforward in order to reduce the implementation cost. Finally, a numerical example is given to illustrate the utility of the proposed technique.